Pompey Reserves suffered a 4-0 defeat at AFC Wimbledon in their second of three Central League Cup group games.
The result means that they cannot qualify for the knockout stages, whatever the result of next month’s trip to Bournemouth.
There was a mixture of youth and experience on display at the King’s Sports Ground, with Luke McGee, Anton Walkes, Brandon Haunstrup, Danny Rose, Louis Dennis and Joe Mason all featuring.
But the Dons found the target twice in each half to ensure the Blues made the trip home empty-handed.
The visitors received a blow before any meaningful action had taken place, as Mason hobbled off with a groin injury to be replaced by Alfie Stanley.
They did have the first chance of the contest, however, with a shot from Leon Maloney blocked by Tom Scott after the winger had found space on the right.
And Dennis then threaded a pass through to Josh Flint, who missed a decent opportunity by firing past the post.
Luke McGee was called into action at the other end, coming off his line to make a save after Ossama Ashley had sent Tommy Wood clear.
And AFC Wimbledon were ahead on 25 minutes when James O’Halloran’s long throw was flicked on by Wood and Bobby Mills brought the ball down neatly before finding the net.
McGee then made a sharp stop to deny Osaze Urhoghide, while Kosta Sparta’s shot was narrowly off target after the midfielder had seized on a loose ball.
The hosts were totally on top and doubled their advantage just before the interval, as Wood was fed by Kyran Stabana down the right and crossed for O’Halloran to head home.
Half Time: AFC Wimbledon 2 Pompey 0
Pompey started the second half brightly, although a volley from Dennis lacked power and was easily gathered by Nik Tzanev.
Dennis and Oscar Johnston also sent efforts narrowly wide, as the Blues searched for a route back into the game.
But their opponents effectively sealed the win on 65 minutes when Sparta weaved into the box and teed-up Wood to slot past McGee.
And the scoreline became even more emphatic seconds later, as – with the visitors defence in disarray – Wood tapped in from close range.
Sparta also went close, but the game soon become mired in mediocrity, with the hosts knowing they had completed the task at hand.
AFC Wimbledon: Tzanev; Stabana, Collins, Urhoghide, Scott; Rudoni, Ashley, Sparta, O’Halloran; Mills, Wood (Lodge-Francis 77)
Subs not used: White, Madelin, Procter
Pompey: McGee; Walkes, Robb, Mnoga, Haunstrup; Read, Rose; Maloney, Dennis, Flint; Mason (Stanley 2 (Johnston 57))
Subs not used: L.Pitman, Kavanagh, Bridgman
Referee: Stuart Kyle